It’s Gigi Hadid’s 21stbirthday (she’s in good company — it’s Shakespeare’s, too!), and to celebrate the momentous occasion, the model did something TOTALLY unexpected — she (gasp!) went brunette! Pictured in this snap from Bella’s Instagram that simply reads “birthday gal,” the formerly blonde bombshell is twinning hardcore with her younger sis.

Though it wouldn’t be the first time Gigi has toyed with the dark side (she recently donned a chocolate hue for a Balmain runway), or even a big hair change (you might recall those bangs she rocked at the MTV Movie Awards?), it’s too early to tell if this is a permanent change or something more temporary. Is this real dye? A wig? Could it possibly even be a throwback? We’ve got so many questions, and so few answers, but one thing’s for sure: The Hadid sisters look great.

Happy b-day Gigi!

What do you think of Gigi’s new look? Let us know over @BritandCo!

Photos via @bellahadid and Dimitrios Kambouris/Getty